The invention relates generally to components for injection molding machines and more specifically to an articulated core blade for incorporation into injection molding machines which facilitates release of undercuts and similar features in molds.
The formation of undercuts and similar features in injection molded products typically requires the incorporation of moveable mold components. Such components are generally referred to as core blades.
Core blades are received within complementary passageways in the lower mold block and are coupled to an ejector plate which moves relative to the mold block. In a first position, the core blade is seated within the lower mold half and in this position forms the appropriate and required undercuts or similar features such as apertures having axes disposed in nonperpendicular orientations relative to the mold parting line. In a second position, the ejector plate has moved toward the lower mold block, raising the core blade while simultaneously translating it laterally, away from the undercut or aperture thereby releasing the molded part.
The technology of such moveable core components is represented in patented art. For example, U.S. Pat. No. 2,147,217 teaches a mold having side walls pivoted by knuckle joints which forms an undercut in the side walls of the product. U.S. Pat. No. 2,859,478 also teaches a pivoting mold component utilizing a knuckle joint.
U.S. Pat. No. 3,523,344 presents an apparatus for pressing ceramic tile wherein an articulated linkage ejects the completed product from the mold. In U.S. Pat. No. 3,813,203, a pair of pivoted arms are coupled by a pneumatic cylinder. The arms operate to open and close the outer ring of a mold utilized to form concrete pipe.
U.S. Pat. No. 4,383,670 discloses a method and apparatus for casting or molding cages for rolling elements. Pairs of slides having obliquely oriented outer, mating surfaces cooperate to form pockets in the cages. U.S. Pat. No. 5,062,208 discloses a similar method and apparatus wherein pairs of obliquely divided halves of a mold insert are mated to form generally spherical openings in a bearing separator.
U.S. Pat. No. 4,854,849 discloses an injection mold having undercut portions which utilize conventional guide pins which are coupled at their lower extremities to sliders and guides. Such sliders are prone to sticking and malfunction if not continually and properly lubricated. At their upper extremities, the guide pins are rigidly secured to mold segments which translate away from the molded product to effect release of same from the mold.
It is apparent from a review of the foregoing prior art that improvements in core blade technology are both possible and desirable.